I had two requirements when I was thinking about (and searching online for) ideas--
1. It had to be relatively easy - not too involved. (I am a low-key teacher after all.)
2. It had to be the kids' work. I didn't want to choose something that had me doing all the work, or even most of the work. I wanted the final product to reflect the child - his ideas and his creativity.
We used sandpaper, crayons, and an iron. They turned out great!
For details, see my post on Pre-K and K Sharing.